Anodic Behaviour Of Tin Research Articles

Electrochemical behavior of tin anode in ascorbic acid solutions

The anodic behavior of tin in ascorbic acid (AA) solutions was investigated using cyclic and/or linear sweep voltammetry and chronopotentiometry method and complemented by XRD and SEM examination. The results showed that the cyclic voltammetric curves in 0.5 M ascorbic acid at 18 ± 0.5 °C involves active/passive transition followed by pitting corrosion. In the active region, Sn dissolves as Sn2+ and Sn4+ and dissolution process is under diffusion control. Passivation is due to deposition of Sn(OH)4 and/or SnO2 on the electrode surface. Pitting corrosion is attributed to local dissolution of the passive film by the adsorbed AA molecules and initiating of pitting attack at a pitting potential Eb. Increasing the acid concentration and temperature enhances the anodic dissolution and shifts Eb to more active direction. Addition of Cl−, Br− and I− in AA enhances both the anodic dissolution and pitting corrosion of Sn. The extent of enhancements depends upon the type and concentration of halide added. The chronopotentiometry curves at constant current densities revealed that increasing the imposed current density decreases the time needed to passivation tp. Addition of low concentrations of Cl−(<5 × 10−5 M) in 0.5 M AA induces pitting corrosion while higher concentrations of Cl− prevent the passivation and the electrode remains in its active state.

ChemInform Abstract: The Anodic Behavior of Tin in Sulfuric Acid Solutions

ChemInform Abstract: The Anodic Behavior of Tin in Sulfuric Acid Solutions

Electrochemical studies on the anodic behavior of tin in citrate buffer solutions

Abstract Chronopotentiometry combined with impedance measurements are used to derive information about the structure and composition of the anodic film formed on tin in citrate buffer and to obtain properties of the anodic film itself. The results of the applied electroanalytical approach indicate that the passive film consists of a layered structure with at least three components. The inner layer is most likely SnO with a thickness of monomolecular dimensions, the thicker intermediate layer contains SnO 2 and finally, the outer layer is primarily Sn(OH) 4 with constant thickness. Structure and composition fully agree with a model of the passive layer on tin recently developed and based on XPS measurements under comparable working conditions. Moreover, excellent agreement was also found in relation to each layer thickness and thickness dependences on the anodization potential. Consequently, it must be emphasized that this study employs a valuable electroanalytical methodology for in situ analysis of passive films on metals.

Anodic behavior of tin, indium, and tin–indium alloys in oxalic acid solution

The anodic behavior of tin, indium, and tin–indium alloys was studied in oxalic acid solution using potentiodynamic technique and characterized by X-ray diffraction and scanning electron microscopy. The E/I curves showed that the anodic behavior of all investigated electrodes exhibits active/passive transition. In the case of tin, the active dissolution region involves two anodic peaks (I and II) prior to permanent passive region. On the other hand, the active dissolution of indium involves four peaks (I–IV) prior to permanent passive region. The first (I) can be associated with the active dissolution of indium to InOOH, the second peak (II) to the formation of In(OH)3, the third peak (III) to partially dehydration of In(OH)3, and the peak (IV) to complete dehydration of In(OH)3 to In2O3. When the surface is entirely covered with In2O3 film, the anodic current falls to a small value (I pass) indicating the onset of passivation. The active dissolution potential region of the first three tin–indium alloys involves a net anodic contribution peak, and this is followed by a passive region. It is expected that the investigated peak is related to the formation of In2O3 and SnO (mixed oxides). When the formation of oxides (the oxides of In and Sn) exceeds its dissolution rate, the current drops, indicating the onset of passivation precipitation of In2O3/SnO and SnO2 on the surface which blocks the dissolution of active sites. The alloys IV and V showed small second peak at about −620 mV which may be related to oxidation of In to In2O3 due to high In content in the two examined alloys. The active dissolution and passive current are increase with increasing temperature for all investigated metals and their alloys.

Anodic behaviour of tin in citrate solutions: The IR and XPS study on the composition of the passive layer

Anodic behaviour of tin in citrate buffer solution (pH 2−5) was studied by potentiodynamic technique. The current-voltage polarization curves were found to exhibit active-passive transition state; the anodic dissolution of tin in the active region was associated with formation of tin(II) citrate complexes SnH x Cit (1 − x)−. . Chloride ions were shown to retard tin passivation due to the pitting corrosion, and this phenomenon was used to increase the passive layer thickness. The composition of the passive layer formed on tin under its anodic polarization in citrate buffer solution in the presence of chloride ions was investigated using infrared and X-ray photoelectron spectroscopies. According to the experimental data, the passive layer mainly represents coordination compound of tin(II) and citrate ions.

Oxide/hydroxide films on tin. Part I: Kinetic aspects of the electroformation and electroreduction of the films

The anodic behaviour of tin in borate solutions has been studied by linear potential sweep voltammetry and triangularly modulated triangular potential sweeps. It is shown that the active to passive transition involves the formation of intermediate soluble species followed by the precipitation of a tin oxide/hydroxide layer that passivates the electrode. The potentiodynamic current-potential behaviour is adequately described by using the Layer-pore-resistance model. A good agreement between experimental and theoretical curves is obtained which allow us to demonstrate that primary passivation of tin in alkaline borate solutions (pH 8.9) as well as the film electroreduction is mainly controlled by the resistance of the electrolyte in the pores of the layer. In addition, the triangularly modulated triangular potential sweep method is applied in order to analyze the existence of reaction intermediates.

Anodic behaviour of tin in maleic acid solution and the effect of some inorganic inhibitors

The anodic behaviour of a tin electrode in maleic acid solutions was investigated by potentiodynamic and chronopotentiometric methods. Measurements were conducted under different experimental conditions. The results demonstrated that the polarization curves exhibit active/passive transition. In active regions, tin dissolves as Sn 2+ which is subsequently oxidized to Sn 4+ and the dissolution process is controlled partly by diffusion of the solution species. The passivity is due to the presence of thin film of SnO 2 on the anode surface formed by dehydration of precipitated Sn(OH) 4. The active dissolution of tin increases with increasing acid concentration, temperature and scan rate. The potential transients showed that the passivation time decreases with increasing applied current density. The effect of adding increasing concentrations of CrO 4 2−, MoO 4 2− and NO 2 − ions on the anodic behaviour of tin in maleic acid was studied. These ions inhibit the active dissolution of tin and promote the attainment of passivity. The extent of these changes depends upon the type and concentration of the inhibitor.

The anodic behaviour of tin and a lead-tin alloy in sulfuric acid

The anodic behaviour of pure tin and a Pb-10wt.%Sn alloy have been studied in sulfuric acid solutions using the ring-disk technique and potential decay measurements. For Sn in H 2SO 4 the results show that this metal passivates partly at acid concentrations above 3 M. Tin was found to dissolve mainly as Sn(II) ions, but to some extent also as Sn(IV) if the potential is > 3 V. The ex situ analysis of the corrosion layer formed on pure Sn showed that the layer consisted mainly of amorphous SnO. The results for the Pb-Sn alloy showed that Sn dissolves from or through the corrosion layer formed on the alloy as Sn(II) ions. Tin was found to inhibit the formation of PbO 2. The effect of Sn ions dissolved in the solution seemed to be similar to that of Sn as an alloying agent. The ring-disk voltammetric measurements showed that a tin-containing compound is formed on the Pb-Sn alloy. This product is probably a mixed Pb-Sn oxide or tin-doped PbO n .

The anodic behaviour of tin in sulphuric acid solutions

The anodic dissolution and partial passivation of tin in 4.5–8 M sulphuric acid solutions has been studied using rotating ring—disk voltammetry. In the region of active dissolution a Tafel slope of 1/(30 ± 3) mV −1 was measured. This value was found to be independent of acid concentration. A reaction mechanism is presented to explain this slope. It was found that tin dissolves both in the active and partly passive potential region in the form of bivalent tin. Oxidation to the tetravalent state seems to occur only at high anodic potentials. Oxygen evolution starts only at potentials above 3 V (vs. Hg 2SO 4/Hg). Analysis of the passivating film formed on the electrode surface using SEM, XRD, XPS and SIMS showed that the film is mainly tin oxide, SnO, mostly in an amorphic form.

Rotating disc and ring disc electrode studies of tin in neutral phosphate solution

The anodic behaviour of tin in neutral phosphate solution has been investigated by means of a rotating disc and ring disc electrode. During the anodic reaction on the disc, a cathodic current is observed on the ring resulting from the reduction of soluble species produced on the disc at low potential and of oxygen at high potential. The low ring-disc current ratio is due to the formation of insoluble product.

Anodic behaviour of tin in neutral phosphate solution

The oxidation behaviour of tin in neutral phosphate solution at 37°C (pH = 6.7) has been examined by means of cyclic voltammetry, potentiostatic and galvanostatic pulse measurements. The results showed that the anodic reaction is controlled by diffusion. The passivation can be brought about by precipitation of soluble species and by nucleation and growth process at more anodic potential. Analysis of the passive layer indicated that it consists of a mixture of tin hydroxide and tin phosphate, or of tin hydroxide containing adsorbed phosphate species.

Anodic passivation of tin in buffered phosphate electrolyte

The anodic behaviour of tin in buffered phosphate electrolyte (pH=3.1) has been studied by a variety of techniques. A number of anodic processes occur depending on potential and the conditions at the electrode/electrolyte interphase. On anodic polarisation the electrode, which is probably filmed with a phosphate layer, initially undergoes dissolution to form probably Sn(H2PO4·HPO4)− species. Impedance data indicate that this process has a corresponding Tafel slope of ∼0.046 V/decade. At more positive potentials three consecutive passivating processes occur. The primary passivating process involves the blocking of the electrode by Sn3(PO4)2 by a dissolution-precipitation mechanism. The formation of SnO by a slow three dimensional nucleation and growth process constitutes the second. It is formed as a result of the attainment of alkaline conditions at the electrode surface. There is also a parallel reaction path involving the formation of soluble Sn(II) species. The tertiary process consists of the oxidation of Sn to Sn(IV) species. Passivation occurs via a dissolution-precipitation mechanism when the electrode is blocked by SnO2. The relative quantities of SnO and SnO2 produced is a function of operating conditions.

Anodic passivation of tin in buffered phosphate electrolyte

The anodic behaviour of tin in buffered phosphate electrolyte (pH=3.1) has been studied by a variety of techniques. A number of anodic processes occur depending on potential and the conditions at the electrode/electrolyte interphase. On anodic polarisation the electrode, which is probably filmed with a phosphate layer, initially undergoes dissolution to form probably Sn(H 2PO 4·HPO 4) − species. Impedance data indicate that this process has a corresponding Tafel slope of ∼0.046 V/decade. At more positive potentials three consecutive passivating processes occur. The primary passivating process involves the blocking of the electrode by Sn 3(PO 4) 2 by a dissolution-precipitation mechanism. The formation of SnO by a slow three dimensional nucleation and growth process constitutes the second. It is formed as a result of the attainment of alkaline conditions at the electrode surface. There is also a parallel reaction path involving the formation of soluble Sn(II) species. The tertiary process consists of the oxidation of Sn to Sn(IV) species. Passivation occurs via a dissolution-precipitation mechanism when the electrode is blocked by SnO 2. The relative quantities of SnO and SnO 2 produced is a function of operating conditions.

Anodic Behaviour of Tin in Potassium Hydroxide Solution

Results of galvanostatic polarisation of tin anodes in potassium hydroxide solutions are reported.The orientation of the anode plays an important part in the observed behaviour. Permanent passivity occurs when the potential rises to that required for oxygen evolution from a film of stannic oxide, 50–100 Å, thick. At [KOH] up to and including 7 M, the prepassivation ‘active’ region of the potential–time behaviour conforms to a ‘solution-controlled’ reaction; at higher [KOH] anode films are formed with less and less dependence on mass transport in the electrolyte.Interpretations of the observed behaviours are given.

Electropolishing in Organic Electrolyte Solutions

SummaryDetails of experimental studies of the electropolishing of a number of metals in 10% sulphamic acid- formamide solutions are given. Iron, cadmium, zinc and tin polished and etched well in this system. Copper and uranium also polished but remained unetched at low current densities. Molybdenum and tungsten were also studied. Satisfactory etching and polishing of these metals was not achieved. Dissolution efficiencies were determined for Fe, Cu, Sn, Cd, Zn and U. The anodic behaviour of tin was studied in more detail in order to correlate the electrochemical conditions with the nature of the metal surface produced. The purity of the formamide used had some effect upon the anodic polarization characteristics of tin inasmuch as the limiting current density region was not clearly defined and the change in potential was only ∼0·5V whereas in purified solutions this was much more clearly defined and existed over a potential range of ∼4V. There was no evidence that impurities in the formamide affected the n...

The anodic behaviour of tin in alkaline solutions—I. 0·1 M sodium borate solution

When an oxide-free tin surface is anodically polarized in deaerated 0.1 M sodium borate at a c.d. of about 6μA/cm 2 the potential of the tin remains constant at first at −0·85 V vs. Ag/AgCl. Half the current is used for oxide formation and half for tin dissolution. This process continues even when the potential becomes more positive until a potential of +0·2 V vs. Ag/AgCl is attained. The stannous oxide is then oxidized to stannic oxide until the oxygen-evolution potential is reached, when the oxidation ceases. The presence of stannic oxide leads to a characteristic “kink” in the cathodic reduction curve.

The anodic behaviour of tin in alkaline solutions—II. 0·1 M sodium carbonate and 0·005 M potassium chromate solutions

Tin anodically polarized in 0·1 M sodium carbonate solution shows similarity to polarization in 0·1 M sodium borate only at the higher current densities, e.g. 56 μA/cm 2. This is due to the high solubility of tin oxides in deaerated sodium carbonate. At low current densities passivation does not take place. In contrast, passivation in 0·005 M potassium chromate solution occurs at a very low current density, 2·8 μA/cm 2. Stannous oxide is oxidized to stannic oxide above a potential of +0·2 V relative to Ag/AgCl. In the case of the chromate solution, however, the oxide-film thickness increases even after the oxygen-evolution potential is reached, which does not occur in carbonate or borate solution.

The Anodic Behavior of Tin in an Alkaline Solution

The Anodic Behavior of Tin in an Alkaline Solution

Observations on the internal corrosion of tin‐plate cans by acid foodstuffs

AbstractBy calculating from Nernst's equation the potentials of tin and iron, it is shown that the anodic behaviour of tin vs. iron in the corrosion of tin plate by canned foods is what would be expected on theoretical grounds. With reference to the fact that the hydrogen evolved during the corrosion of tin plate is less than the amount corresponding to the metals dissolved, an electrochemical mechanism is suggested which may account in part for this deficit. Attention is also drawn to previously unsuspected accelerators of corrosion, e.g. caramelization products in fruits. It is interesting to note that while caramel from dextrose acts as an efficient accelerator, caramel from sucrose has no effect.

A High‐Efficiency Anode for Alkaline Tin‐Plating: The Effect of Alloying Constituents on the Anodic Behavior of Tin in Alkaline Stannate Solutions

By incorporating up to about 1 per cent of aluminum in the tin anodes used in alkaline tin plating, the current densities obtainable can be markedly increased. The effect of twenty‐six elements upon the anode behavior of tin in alkaline solutions has been studied. Many have little effect in the quantities tested, i.e., up to about 1 per cent; some, such as nickel, silver, cadmium, and indium have a strong passivating action. Among the several which tend to increase anode efficiency, aluminum appears most promising from a practical standpoint, since it alloys smoothly and easily with tin, is nonpoisonous, cheap, produces no observable deleterious effect on the bath, and forms alloys which are stable and of good mechanical properties.This investigation placed principal emphasis upon the potassium stannate bath, but enough work was done with the sodium stannate solution to show that the benefits of the aluminum alloy are common to both.